TECTONOTHERMAL MODEL FOR THE LATE PALEOZOIC SYNCOLLISIONAL FORMATION STAGE OF THE KARA OROGEN (northern Taimyr, Central Arctic)
V.A. Vernikovsky1,2, O.P. Polyansky3, A.V. Babichev3, A.E. Vernikovskaya1,2, V.F. Proskurnin4, N.Yu. Matushkin1,2
1Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
2Novosibirsk State University, ul. Pirogova 1, Novosibirsk, 630090, Russia
3V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
4A.P. Karpinsky Russian Geological Research Institute, Srednii pr. 74, St. Petersburg, 199106, Russia
Keywords: Collision, anatexis, granite, U-Th-Pb geochronology, thermomechanical modelling, Arctic, Kara orogen, Taimyr, Kara microcontinent, Siberian craton, finite element method, heat sources
Abstract
We present a tectonothermal model for the late Paleozoic syncollisional formation stage of the Kara orogen in northern Taimyr in the Central Arctic. The model is based on new and published structural, petrological, geochemical, and geochronological data, as well as thermophysical properties obtained for the Kara orogen. The latter hosts a significant volume of granites formed as a result of the collision between the Kara microcontinent and the Siberian craton. Based on geological, geochemical, and U-Th-Pb isotope data, the granites were differentiated into syncollisional and postcollisional intrusions that were emplaced in the intervals 315-282 Ma and 264-248 Ma, respectively. The presented tectonothermal model covers only the syncollisional formation stage of the Kara orogen, during which anatectic granites formed. The 2D models help to reconstruct the main tectonothermal processes of the syncollisional stage of formation of this structure, taking into account the local peculiarities of the thermal state of the Earth’s crust in the region. The model shows the mechanisms of increase in the lower crust temperature necessary for the formation of syncollisional anatectic granites. The estimates obtained from the model constrain the time interval between the collision/tectonic stacking and the granite formation. The modeling also showed the general regularities typical of orogens at syncollisional stages.
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